Co/SiO2 composite particles with high electromagnetic wave absorbing performance and weather resistance

Co/SiO2 composite particles were prepared by fabricating SiO2 shell on the surfaces of dendritic Co particles. The effects of SiO2 shell and annealing treatment on microstructure evolution and performance improvement of Co/SiO2 composite particles were investigated. It was found that, Co/SiO2 composite particles exhibited weather resistance when exposed to high temperature air or diluted hydrochloric acid. Coatings containing Co/SiO2 composite particles as fillers presented high electromagnetic wave absorbing efficiency and thin matching thickness. The weather resistance and the electromagnetic wave absorbing performance were further improved after an annealing treatment.

► Co/SiO2 composite particles with core–shell structure were fabricated.
► Microstructure evolution of Co and SiO2 shell during annealing was examined.
► Excellent oxidation/corrosion resistance and EMA performance were obtained.
► An annealing process was developed to further improve the EMA performance of Co/SiO2.